2. Move project dependencies to consume vendored guava from :beam-vendor-grpc-1_13_1 project rather than the published Maven artifact.

Consuming from the integrated project artifact (#2) was necessary in order to make the changes and validate them inline without needing to first publish a Maven release. However, this has some downsides: notably, IntelliJ struggles to understand shaded dependencies [3]. I believe we should move back to consuming pre-published vendor artifacts. The first step is to publish a new vendored beam-vendor-grpc-1_13_1 artifact; I can start that process.